/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.zookeeper.server.persistence;

import java.io.File;
import java.io.IOException;
import java.util.Map;

import org.apache.zookeeper.server.DataTree;

/**
 * snapshot interface for the persistence layer. implement this interface for
 * implementing snapshots.
 */
public interface SnapShot {

	/**
	 * free resources from this snapshot immediately
	 * 
	 * @throws IOException
	 */
	void close() throws IOException;

	/**
	 * deserialize a data tree from the last valid snapshot and return the last zxid
	 * that was deserialized
	 * 
	 * @param dt       the datatree to be deserialized into
	 * @param sessions the sessions to be deserialized into
	 * @return the last zxid that was deserialized from the snapshot
	 * @throws IOException
	 */
	long deserialize(DataTree dt, Map<Long, Integer> sessions) throws IOException;

	/**
	 * find the most recent snapshot file
	 * 
	 * @return the most recent snapshot file
	 * @throws IOException
	 */
	File findMostRecentSnapshot() throws IOException;

	/**
	 * persist the datatree and the sessions into a persistence storage
	 * 
	 * @param dt       the datatree to be serialized
	 * @param sessions
	 * @throws IOException
	 */
	void serialize(DataTree dt, Map<Long, Integer> sessions, File name) throws IOException;
}
